A collapsible baby playing bed, as shown in FIG. 8, was disclosed in U.S. Pat. No. 5,381,570 and issued on Jan. 17 1995, wherein a bending joint 8, referring to FIGS. 7 and 8, was provided. The bending joint 8 comprises an inner tooth member 81, a spring 82, a fitting block 83, a bending member 84, a bolt 85, and a push cap 86.
In combination, the fitting block 83 is inserted among inner tooth portions 811 of the inner tooth member 81 with a spring 82 being placed between the block 83 and the tooth member 81; the bending member 84 is mounted on the block 83 with opposing sectorial projections 841 thereof being mounted on opposing sectorial recesses 831 of the block 83; the bolt 85 is used for the bending member 84, the fitting block 83, the spring 82, and the tooth member 81 to be screwed together in that sequence; and the cap 86 is fitted on the bending member 84.
A tubular portion 842 of the bending member 84 and a tubular portion 812 of the inner tooth member 81 are connected with an upper frame 9. Because an uppermost portion of the bending joint 8 is arranged to be as high as the bed, an end 91 of each upper frame 9 is bent to be able to be inserted into the tubular portions 842, 812.
The above described combination is known to have disadvantages as follows:
1. the end 91 is bent and so the upper frame 9 requires greater circumferential thickness than a pipe of the same kind with an unbent end to maintain one strength that both the cost and the weight of the bed is undesirably increased; PA1 2. the end 91 bent looks unpleasant aesthetically; and, PA1 3. customers have to pay higher price to buy the bed due to said cost increase.